deduplicate functions

cng/sha3.go

@@ -58,16 +58,9 @@ func SumSHAKE256(data []byte, length int) []byte {
 	return out
 }
 
-// SupportsSHAKE returns true if the SHAKE extendable output function with the
-// given securityBits is supported.
+// SupportsSHAKE returns true if the SHAKE and CSHAKE extendable output functions
+// with the given securityBits are supported.
 func SupportsSHAKE(securityBits int) bool {
-	// CNG implements SHAKE using CSHAKE with empty N and S.
-	return SupportsCSHAKE(securityBits)
-}
-
-// SupportsCSHAKE returns true if the CSHAKE extendable output function with the
-// given securityBits is supported.
-func SupportsCSHAKE(securityBits int) bool {
 	var id string
 	switch securityBits {
 	case 128:

cng/sha3_test.go

@@ -34,14 +34,10 @@ var testShakes = map[string]struct {
 func skipCSHAKEIfNotSupported(t *testing.T, algo string) {
 	var supported bool
 	switch algo {
-	case "SHAKE128":
+	case "SHAKE128", "CSHAKE128":
 		supported = cng.SupportsSHAKE(128)
-	case "SHAKE256":
+	case "SHAKE256", "CSHAKE256":
 		supported = cng.SupportsSHAKE(256)
-	case "CSHAKE128":
-		supported = cng.SupportsCSHAKE(128)
-	case "CSHAKE256":
-		supported = cng.SupportsCSHAKE(256)
 	}
 	if !supported {
 		t.Skip("skipping: not supported")